The present invention relates to a pump, for example, for pumping lubricating oil of an internal combustion engine, in particular a multistroke vane-cell pump, having a rotor and vanes which are at least radially displaceable in rotor slots, whose vane heads slide along a stroke contour, the stroke contour having, among other things, a radial outlet opening, which is closeable by a valve device.
Such pumps are known. Thus, for example, a multistroke vane-cell pump whose stroke contour is made of sheet metal is known. In this pump, the switchable second pumping stage is directly connected to the intake area of the first pumping stage via a radial groove in the sheet metal contour in the event of low temperature of the lubricating oil, so that at a low temperature only the first stage of the double-stroke vane-cell pump pumps. When the temperature increases, the switching stage, i.e., stage 2 of the vane-cell pump, is closed by an element which is adjustable as a function of the temperature, in such a way that the second stage of the double-stroke vane-cell pump also pumps the lubricating oil under pressure into the lubricating oil channels of the engine. The temperature-dependent switching also closes this radial groove and the volume flow is supplied to the system pressure area via a check valve. The valve, which is adjustable as a function of the temperature, is opened and closed with the aid of a conical seat. The disadvantage of this approach is the small flow cross sections that may be achieved, resulting in an excessive pressure drop; in addition, the flow around the valve seat results, for part of the volume flow, in a flow directed against the actual intake volume flow. These flows result in losses which cause an early onset of cavitation in the intake area. Furthermore, the manufacture of the seat valve is very complicated and is therefore expensive.